linux-kernel - Re: [PATCH] misc: rtsx: Set setting

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Date:   Thu, 19 May 2022 14:18:59 -0700
From:   Tom Rix <trix@...hat.com>
To:     Nathan Chancellor <nathan@...nel.org>,
        Ricky WU <ricky_wu@...ltek.com>, miquel.raynal@...tlin.com
Cc:     Kai-Heng Feng <kai.heng.feng@...onical.com>,
        "arnd@...db.de" <arnd@...db.de>,
        "gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
        "ndesaulniers@...gle.com" <ndesaulniers@...gle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "llvm@...ts.linux.dev" <llvm@...ts.linux.dev>
Subject: Re: [PATCH] misc: rtsx: Set setting_reg2 before use.


On 5/19/22 1:57 PM, Nathan Chancellor wrote:
> On Tue, May 17, 2022 at 08:10:17AM +0000, Ricky WU wrote:
>>> -----Original Message-----
>>> From: Kai-Heng Feng <kai.heng.feng@...onical.com>
>>> Sent: Tuesday, May 17, 2022 9:53 AM
>>> To: Tom Rix <trix@...hat.com>
>>> Cc: Nathan Chancellor <nathan@...nel.org>; arnd@...db.de;
>>> gregkh@...uxfoundation.org; ndesaulniers@...gle.com; Ricky WU
>>> <ricky_wu@...ltek.com>; linux-kernel@...r.kernel.org; llvm@...ts.linux.dev
>>> Subject: Re: [PATCH] misc: rtsx: Set setting_reg2 before use.
>>>
>>> On Tue, May 17, 2022 at 1:06 AM Tom Rix <trix@...hat.com> wrote:
>>>>
>>>> On 5/16/22 8:56 AM, Nathan Chancellor wrote:
>>>>> On Mon, May 16, 2022 at 09:00:47AM -0400, Tom Rix wrote:
>>>>>> The clang build fails with
>>>>>> rts5261.c:406:13: error: variable 'setting_reg2' is used uninitialized
>>> whenever 'if' condition is false [-Werror,-Wsometimes-uninitialized]
>>>>>>           } else if (efuse_valid == 0) {
>>>>>>                      ^~~~~~~~~~~~~~~~
>>>>>>
>>>>>> setting_reg2 is set in this block
>>>>>>     if (efuse_valid == 2 || efuse_valid == 3) { ..
>>>>>>     } else if (efuse_valid == 0) {
>>>>>>       // default
>>>>>> ..
>>>>>>     }
>>>>>> But efuse_valid can also have a value of 1.
>>>>>> Change the 'else if' to 'else' to make the second block the default.
>>>>>>
>>>>>> Fixes: b1c5f3085149 ("misc: rtsx: add rts5261 efuse function")
>>>>>> Signed-off-by: Tom Rix <trix@...hat.com>
>>>>> I am not sure if this fix is correct from a functional standpoint (i.e.
>>>>> is treating efuse_valid == 1 the same as efuse_valid == 0 correct?)
>>>>> but it is better than not handling this value altogether. For what
>>>>> it's
>>>>> worth:
>>>> I looked at how the code used to work, this seemed better than
>>>> initializing to NULL.
>>> Or maybe use a single if block?
>>>
>>> u16 setting_reg1 =PCR_SETTING_REG1 , setting_reg2 =
>>> PCR_SETTING_REG2; ...
>>> if ((efuse_valid == 2 || efuse_valid == 3) && (valid != 3) {
>>>      setting_reg1 = PCR_SETTING_REG4;
>>>      setting_reg2 = PCR_SETTING_REG5;
>>> }
>>>
>>> Kai-Heng
>>>
>>>>> Reviewed-by: Nathan Chancellor <nathan@...nel.org>
>>>>>
>>>>> As a side note, it is unfortunate that this change made it into
>>>>> -next when there was an outstanding report about this warning:
>>>>   From the clang side, this is a build break and my static analysis
>>>> infra goes down.
>>>>
>>>> These build breaks seem to happening every week, is there a precommit
>>>> clang gating test that could be done for -next ?
>>>>
>>>> Tom
>>>>
>>>>> https://lore.kernel.org/202205100220.WyAyhKap-lkp@intel.com/
>>>>>
>>>>>> ---
>>>>>>    drivers/misc/cardreader/rts5261.c | 2 +-
>>>>>>    1 file changed, 1 insertion(+), 1 deletion(-)
>>>>>>
>>>>>> diff --git a/drivers/misc/cardreader/rts5261.c
>>>>>> b/drivers/misc/cardreader/rts5261.c
>>>>>> index 749cc5a46d13..f22634b14dc8 100644
>>>>>> --- a/drivers/misc/cardreader/rts5261.c
>>>>>> +++ b/drivers/misc/cardreader/rts5261.c
>>>>>> @@ -403,7 +403,7 @@ static void rts5261_init_from_hw(struct rtsx_pcr
>>> *pcr)
>>>>>>                       setting_reg1 = PCR_SETTING_REG4;
>>>>>>                       setting_reg2 = PCR_SETTING_REG5;
>>>>>>               }
>>>>>> -    } else if (efuse_valid == 0) {
>>>>>> +    } else {
>>>>>>               // default
>>>>>>               setting_reg1 = PCR_SETTING_REG1;
>>>>>>               setting_reg2 = PCR_SETTING_REG2;
>> Sorry for the trouble
>> here can be changed to
>> ...
>> } else if (efuse_valid == 0) {
>> 		// default
>> 		setting_reg1 = PCR_SETTING_REG1;
>> 		setting_reg2 = PCR_SETTING_REG2;
>> } else {
>>   return;
>> }
>> Because other values are invalid
> Tom, were you going to send a v2 of this?

No.

Miquèl has the best fix.

https://lore.kernel.org/lkml/20220518170920.4db16990@xps-13/

Tom


>
> Cheers,
> Nathan
>